Stent graft with fixing elements and insertion system

ABSTRACT

The present invention relates to a stent graft and to an insertion system for the stent graft according to the invention. The stent graft comprises a stent graft portion with a self-expanding stent having successive rings of meandering supports and a first prosthesis material secured on the rings. On at least one of its rings, the stent graft portion has two loop-shaped fixing elements which are attached via a common fixing area and which are attached to the supports of the rings in such a way that, due to the fact that they are guided in opposite directions around the hollow cylindrical body, the latter is compressible. Furthermore, the insertion system according to the invention also has a pin element with which the loop-shaped fixing elements can be threaded on.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/445,795, filed Jul. 29, 2014, which is a continuation ofinternational patent application PCT/EP2013/052584, filed on Feb. 8,2013, designating the U.S., which international patent application hasbeen published in German language and claims priority from German patentapplication DE 10 2012 101 103.6, filed on Feb. 10, 2012. The entirecontents of these priority applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a stent graft having a hollowcylindrical body with a blood side and a vessel side, wherein the stentgraft has a first stent graft portion with a self-expanding stentcomposed of successive rings of meandering supports in its longitudinaldirection, and with a first prosthesis material secured on the rings andconnecting these on the vessel side of the hollow cylindrical body.

Stent grafts of this kind are well known in the prior art. Thesevascular stents, also referred to as intravascular or intraluminal stentgrafts, or stents for short, are implanted into blood vessels that havebeen damaged, for example as a result of diseases or the like, or thathave been widened by an aneurysm or have had their lumen occluded, as aconsequence of which the function of the vessels is greatly impaired orthere is a risk of the vessels rupturing. In the prior art, variousimplantable stent devices are known which, after they have beenimplanted, keep blood vessels, for example arteries, open or delimitaneurysms from the blood stream. Such stents generally have a tubular orhollow cylindrical body which is inserted into the vessel and is fixedat the appropriate location in order to keep the lumen of the vesselopen.

Thus, the prior art includes stent grafts, for example, which have awire framework made of a self-expanding material, for example Nitinol,wherein the wire framework can additionally be connected to a tube madeof textile or PTFE.

For implantation, the stent or stent graft is radially compressed, suchthat its cross-sectional surface area can be considerably reduced and itcan be easily inserted into the vessel. On account of the resiliency ofthe metal framework or metal stent, the stent expands back to itsoriginal shape and in so doing stretches its jacket surface, whichwedges itself internally in the blood vessel.

For implantation, the stents are folded up radially and, with the aid ofcatheters advanced through the lumen, are then inserted into the bloodvessel and placed in the correct position in the vessel. The correctposition of the stent can be monitored using X-ray markers, for example.To ensure that the stents remain in the folded-up state during theirpositioning, they are usually arranged in a sheath or in a sheath-liketube, which presses the stent radially inward and compresses it. Thisso-called withdrawal tube is pulled back after the stent has beenpositioned in the vessel, in which process the stent is held axially byan abutment element/slide element, which is also designated as a pusher.The pusher lies in contact with the stent and holds the latter in itsaxial position, while the withdrawal sleeve also surrounding the pusheris detached from the stent, which is thus able to expand and wedgeitself in the blood vessel.

When releasing a self-expanding stent or stent graft, the physicianoften has to apply a considerable force to the pulling grip of thesleeve tube and to the grip used for positioning the implant andconnected to the pusher. Besides the force applied, a further criticalpoint is often that the stent, once released, can no longer be rotatedor moved in the vessel in order, if necessary, to position it correctly,since otherwise there is a danger of damaging the vessel.

DE 103 35 948 B3 discloses a stent whose support framework is compressedby a thread that is looped around it. The ends of the thread arediverted from the outside into the support framework and are coupledthere.

WO 2011/063972 A1 discloses an insertion system for introducing amedical implant into a vessel of a patient, wherein at least one pullingthread is used with which the diameter of an implant can be changed.

Moreover, US 2007/0100427 A1 describes a device having an intraluminalprosthesis with two thread-like connection elements which enclose theprosthesis in the distal and proximal areas and which can compress theprosthesis by being shortened.

Finally, U.S. Pat. No. 5,776,186 describes an insertion device for stentgraft systems that have two Nitinol wire loops which form the frameworkof the stent graft and via which the stent graft is brought to itsexpanded shape after the insertion catheter compressing the stent grafthas been pulled back.

EP 1 964 532 A2 and EP 1 117 341 B1, for example, disclose an insertionsystem which permits step-by-step release of a stent/stent graft keptcompressed by a sleeve tube. Moreover, in the prior art, so-calledpistol grips are known which are intended to allow the physician togently release a stent graft likewise kept compressed by a sleeve tube.

However, the insertion systems described have the disadvantage that itis impossible or almost impossible with them to position the stent,before it is finally released, i.e. to rotate it and move it, in such away that it comes to lie correctly. This is critical especially in thecase of stents/stent grafts with side branches, since these are ofcourse intended to extend into the branching-off blood vessels after thestent/stent graft has been released.

SUMMARY OF THE INVENTION

Against this background, it is an object of the present invention tomake available a stent/stent graft and an alternative release system bymeans of which the stent/stent graft can be easily compressed, insertedand released in such a way that correct positioning of the stent ispossible directly before its final release.

According to the invention, this and other objects are achieved by adevelopment of the stent graft mentioned at the outset, wherein thefirst stent graft portion thereof has, on at least one of its rings, twoloop-shaped fixing elements which are attached via a common fixing areaand which are attached to the supports of the rings in such a way that,due to the fact that they are guided in opposite directions around thehollow cylindrical body, the latter is compressible.

The object is further achieved by an insertion system for a stent graftas described above which, in order to compress and insert the stentgraft into the blood vessel, moreover has at least one pin elementdesigned to be threaded through and temporarily fix the loop-shapedfixing elements compressing the stent graft.

With the stent graft according to the invention and the insertion systemaccording to the invention, it is possible to correctly position thestent graft and, after it has been positioned, to rotate it, ifnecessary, in order to position any side branches of the stent graft inbranching-off vessels. A step-by-step release of the stent graft is alsoachieved, with the individual steps of the release being able to bespecifically controlled.

With the loop-shaped fixing elements attached to the supports of thestent rings, it is possible to compress the stent graft. The twoloop-shaped fixing elements, also designated synonymously as “loops”here and throughout the application, are attached to, preferably sewnonto, the stent rings or supports of the stent graft according to theinvention. The loop-shaped fixing elements are attached, preferably sewnon, in a common fixing area on the supports. This common fixing area canextend over a portion of the support or can be punctiform. In order tocompress the stent graft, one loop of the two loop-shaped fixingelements is guided around to the right, with respect to thecircumference of the stent graft or of the hollow cylindrical body, andone is guided around to the left. The two loops then “meet” at thelocation lying opposite the fixing points of the fixing elements in thecircumference of the hollow cylindrical body, where they can be placedone over the other. In this way, the stent graft can be “tied together”in the area of the fixing elements and thereby compressed.

According to one embodiment of the invention, the loop-shaped fixingelements are made of a thread-like material customarily used inmedicine. For example, it is possible to use the same material that isused for securing the stent rings to the prosthesis material. This canbe, e.g., a synthetic thread, preferably of polyester, polyamide,polytetrafluoroethylene or ultra-high-molecular-weight polyethylene(UHMPE) or mixtures thereof or has said materials.

In another embodiment of the stent graft according to the invention, thestent graft has two loop-shaped fixing areas attached via a commonfixing area or point on each of its rings.

This feature has the advantage that the stent graft can thus becompressed along its entire length.

The loop-shaped fixing elements in the circumference of the hollowcylindrical body of the stent graft can be attached to the supports in amanner offset in relation to one another or adjacent to and behind oneanother.

According to a further embodiment of the stent graft according to theinvention, the first stent graft portion can also have at least onestent side branch, e.g. at least two or three stent side branches,designed to be introduced into a vessel branching off from the bloodvessel.

According to a further embodiment, the stent graft has a second stentgraft portion with a tubular body composed of a second prosthesismaterial, which material can be identical to the first prosthesismaterial or can consist of a different material or have this. The secondstent graft portion has no stent rings. Moreover, according to a furtherembodiment, it may be preferable if this second stent graft portion hasat least one stent side branch, more preferably two or three sidebranches.

The second stent graft portion can be provided in particular for thereconstruction of damaged or injured blood vessels and is generally sewninto such devices in such a way that the areas which are diseased andinjured or damaged, or which are no longer functional or are only partlyfunctional, are replaced by the second stent graft portion. For example,the second stent graft portion can in particular be provided for thereconstruction of the aortic arch and of the ascending aorta, especiallyif this portion has three side branches that are provided respectivelyfor the brachiocephalic trunk, the common carotid artery and the leftsubclavian artery, into which vessels the side branches are inserted inorder to ensure supply of blood to these vessels originating in theaortic arch.

As has been mentioned above, the present invention also relates to aninsertion system for inserting a self-expanding stent graft into a bloodvessel of a patient, wherein a stent graft as described above isintended to be inserted, wherein the insertion system, in order tocompress and insert the stent graft into the blood vessel, moreover hasat least one pin element designed to be threaded through and temporarilyfix the loop-shaped fixing elements compressing the stent graft, and thepin element has a proximal end and a distal end, and a middle portionlying between the proximal end and distal end.

The pin element provided in the insertion system is thus threadedthrough the loops which, starting from their fixing location, have eachbeen guided around the stent graft and thereby compress the latter. Thethreading of the loops means that these are fixed in turn, as a resultof which the stent graft remains compressed as a whole. In thiscompressed form, the stent graft can be inserted into the blood vessel.

Accordingly, upon release, it is thus preferred if the compressed stentgraft can be released by pulling the pin element back in the proximaldirection and thereby freeing the loops that have kept the stent graftcompressed.

Here, “proximal direction” indicates the direction leading toward theuser. Moreover, a “pin element” is understood as any elongate,pin-shaped element that is long enough and of such diameter as to beable to be engaged in at least some of the loops provided on the stentgraft. Consequently, the pin element has a proximal end and a distal endand a proximal and a distal area, and also, between these two ends orareas, a middle area, wherein the proximal end is closest to the user orthe person manipulating the insertion system. The pin elements arepreferably made of stainless steel but can be made of any other desiredmaterial that is suitable for the present purposes and that has acertain or sufficient stiffness to keep the loops and therefore also thestent graft fixed.

When the pin element is pulled back, the loops are thus released againstep by step, as a result of which they are no longer held together atthe location in the circumference of the stent lying opposite the fixinglocation, and the stent is thus no longer compressed and is consequentlyreleased.

According to a further embodiment of the insertion system according tothe invention, it has several pin elements of different length. Theseare designed in such a way, and are threaded through the loop-shapedfixing elements for compressing and releasing the stent graft in such away, that different portions of the stent are releasable by pulling thepin elements of different length back in the proximal direction.

The pin elements are preferably guided with their proximal end through acarrier element and, when the latter is moved in the proximal direction,the pin elements, because of their different length, are carried alongone after another in the proximal direction. In this way, stent areaswhich are fixed/compressed by pin elements of different length canadvantageously be released at different times and in a specific way.

If several pin elements of different length are provided in theinsertion system according to the invention, it is preferable if theloop-shaped fixing elements are attached to the rings of the stent in amanner offset in relation to one another. In this embodiment, each pinelement then engages in a pair of loop-shaped fixing elements. If theloop-shaped fixing elements are attached to the rings in a manneradjacent to one another in the longitudinal direction of the stentgraft, it is preferable if one pin element is used. In this case, theone pin element is threaded through all the pairs of loop-shaped fixingelements.

According to a further embodiment, the insertion system according to theinvention is additionally provided with a sleeve tube which is arrangedover the pin elements compressing the stent in cooperation with theloop-shaped fixing elements.

With this embodiment, it is possible to use both a sleeve tube and alsothe release mechanism of pin element/loop-shaped fixing elements inorder to release the stent graft. This “combined” release mechanism isadvantageous particularly in stent grafts that have side branches orarms issuing from the main body of the stent graft. Here, the wholestent graft in general can first of all be released by pulling back thesleeve tube, in which case the stent graft area with the arms stillremains compressed by the mechanism composed of pin element andloop-shaped fixing elements. In this way, the sidebranches/branching-off arms can first of all be positioned correctly,i.e. in the branching-off vessels, before this area is then alsoreleased by pulling back the one or more pin elements. In this case, thepin element can also be guided through the arm, i.e. in addition to thepassage through the loops.

In another embodiment, provision is also made that the pin element isguided with its proximal end about a roller provided within a handle orhousing of the insertion system.

This embodiment has the advantage that, after pulling back the sleevetube, which is preferably coupled to the handle and is pulled back fromthe stent graft by pulling the handle in the proximal direction, therelease path for the pin elements will still be long enough in orderalso to guide the pins out of the loops and completely release the stentgraft.

It will be appreciated that the insertion system according to thepresent invention also has any other features customary to stentinsertion systems, for example a pusher, catheter tube, etc. Proceedingfrom the teaching disclosed herein, it will be obvious to a personskilled in the art which further features and properties the insertionsystem can have in order to be able to function for the particular use.For example, reference is made to EP 1 964 532, the content of which isexplicitly incorporated herewith.

Further advantages will become clear from the following description ofadvantageous embodiments and from the attached figures.

It will be appreciated that the aforementioned features and the featuresstill to be explained below can be used not only in the respectivelycited combination but also in other combinations or singly, withoutdeparting from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention are shown in the accompanyingfigures and are described in more detail below with reference to thesefigures.

FIG. 1 shows a schematic detail of a first illustrative embodiment ofthe stent graft according to the invention;

FIG. 2 shows a schematic detail of a further illustrative embodiment ofthe stent graft according to the invention;

FIG. 3 shows an enlarged detail of a further embodiment of the stentgraft according to the invention;

FIG. 4 shows a view in which the illustrative embodiment of the stentgraft according to the invention shown in FIG. 1 is in a compressed formwith an engaged pin element;

FIG. 5 shows a detail of an embodiment of a stent graft according to theinvention; and

FIG. 6 shows a schematic view of an embodiment of the release systemaccording to the invention for the stent graft according to theinvention.

DESCRIPTION OF PREFERRED EMBODIMENTS

A first embodiment of a stent graft according to the invention,designated generally by reference sign 10 in FIG. 1, has a hollowcylindrical body 11 with a first stent graft portion 12 having aself-expanding stent composed of successive rings 14 of meanderingsupports (or support elements) 15 in its longitudinal direction. Thesupports 15 are connected to one another on the outside of the hollowcylindrical body 11 by a prosthesis material 17, which is secured on thesupports 15 by stitches 16. The stent graft shown in FIG. 1 also has asecond stent graft portion 18. In contrast to the first stent graftportion 12, this second stent graft portion 18 has no stents composed ofrings with meandering supports, and instead it merely comprises a secondprosthesis material 19.

Moreover, reference signs 20, 21 in FIG. 1 indicate loop-shaped fixingelements or loops, which are situated in pairs on a support 15 of a ring14 and are attached there on a common fixing area 22. In the exampleshown in FIG. 1, the loop-shaped fixing elements 20, 21 are sewn ontothe supports 15 of a ring 14, specifically via a common portion support15, which constitutes the fixing area 22. The loops 20, 21 are the samesize or approximately the same size.

In the figures, the same features of the various embodiments areprovided with the same reference signs. For reasons of clarity, thestitches 16 by which the prosthesis material 17 is connected to therings 14 of the stent are not shown in FIGS. 2 to 5.

Alternatively, in the embodiment shown in the form of a detail in FIG.3, the common fixing area 22′ of the loop-shaped fixing elements 20, 21is attached to the supports 15 in a punctiform manner. Moreover, FIG. 3shows two arrows 26 and 27, which indicate the direction in which thetwo loop-shaped fixing elements 20, 21 are each guided in order to“bind” or compress the hollow cylindrical body 11 of the stent graft 10.

FIG. 2 shows a further embodiment of the stent graft according to theinvention. Here, the second stent graft portion 18 has sidebranches/arms 23, 24, 25, which are provided for introduction into sidevessels branching off from the main vessel.

In FIG. 4, the embodiment of the stent graft 10 according to theinvention shown in FIG. 1 is shown in a partially compressed state.Here, the loop-shaped fixing elements 20, 21 have each been guided indifferent circumferential directions around the hollow cylindrical body11 of the stent graft 12, and then a pin element 26 has been threadedthrough the loops of the loop-shaped fixing elements 20, 21. As can beseen from FIG. 4, if the loops are each guided in opposite directionsaround the stent graft, they meet on the areas 28 which lie opposite thefixing areas 22, 22′ in the circumference of the stent graft 10, wherethe pin element 26 is threaded through them.

FIG. 5 shows a further embodiment of the stent graft according to theinvention, the first stent graft portion 12 here having arms or sidebranches 40, 41, 42 and 43, which are provided for side vesselsbranching off from the main vessel.

The embodiment shown in FIG. 5 can be provided for use, for example, inthe abdominal aorta, such that the stent graft 10 is inserted with itshollow cylindrical body 11 into the abdominal aorta in such a way thatthe side branches 40, 41, 42 and 43 can be placed, for example, in theorigins of the celiac trunk, the superior mesenteric artery and bothrenal arteries. In this embodiment, the pin element 26 can be guidedthrough one of the arms 40, 41, 42, 43 and through the loop-shapedfixing elements 20, 21 compressing the stent graft 10.

FIG. 6 shows schematically a further embodiment of a release systemaccording to the invention. The embodiment of the stent graft 10according to the invention as shown in FIG. 6 also has loop-shapedfixing elements 20, 21, which have each been wound in differentdirections around the stent graft 10. Moreover, several pin elements 27,28, 29, 30 are provided, which are each threaded through a loop pair 20,21. Thus, the pin element 27 is threaded through the loop pair 20, 21designated by A, the pin element 28 is threaded through the loop pair20, 21 designated by B, the pin element 29 is threaded through the looppair designated by C, and the pin element 30 is threaded through theloop pair designated by D.

With their proximal end, that is to say the end closer to the user, thepin elements 27, 28, 29 and 30 are guided through a disk-shaped carrierelement 32 that has four bores 34 through which the pin elements 27, 28,29 and 30 are each guided. At the outermost end of the proximal area ofthe pin elements 27, 28, 29 and 30, there are thickened parts or stopelements 36, of which the diameter is greater than the diameter of thebores 34.

In FIG. 6, arrow 37 indicates the direction in which the pin elementsand the carrier element 32 are guided in order to release the stentgraft 10 or to release individual stent graft areas in succession. Ifthe carrier element 32 is moved in the proximal direction, i.e. towardthe user, it pulls the pin elements 27, 28, 29, 30 with it when it comesinto contact with the thickened part or stop element 36, and itspecifically does so in the sequence in which the stopelements/thickened parts 36 are taken up by the carrier element 32.Thus, in the example shown in FIG. 6, the pin element 30 is the first tobe carried along and pulled in the proximal direction, as a result ofwhich, in the illustrative embodiment shown in FIG. 6, the area D of thestent graft 10 is the first to be released and expanded. As the movementin the proximal direction continues (see arrow 37), the pin element 27is carried along, such that, after the pin element 27 has been pulledout of the loop pair 20, 21, the area A of the stent graft 10 canexpand. Finally, this is followed by areas B and C, which can expand asa result of the sequential carrying of the stop elements 36 of the pinelements 28 and 29 and as a result of these pin elements 28, 29 beingunthreaded from the loop pairs 20, 21.

In this way, depending on the arrangement and threading of the pinelements, any desired areas can be deliberately released at differenttimes.

In a further embodiment (not shown), the pin element 26, or the pinelements 27, 28, 29, 30, can be guided and wound up via its or theirproximal end(s) on a roller located in a handle or housing formanipulating the release/insertion system. This embodiment isparticularly advantageous if, as has been described above, in additionto the release system according to the invention a sleeve tube (notshown in the figures) is also present. This sleeve tube is arranged overthe release system according to the invention composed of loop-shapedfixing elements 20, 21 and pin elements 26, 27, 28, 29, 30 and isconsequently pulled back from the stent graft 10 before the releasesystem according to the invention. Since the sleeve tube is oftencoupled to the handle/housing, and the latter is therefore alreadyguided in the proximal direction, there is generally only a shortrelease path for the pin elements 26, 27, 28, 29, 30, which of coursethen have to be pulled likewise in the proximal direction. By rolling upor winding up the pin elements 26, 27, 28, 29, 30 in the handle, it isensured that the release path is still long enough to pull the pinelements 26 or 27, 28, 29, 30 out of the loop-shaped fixing elements 20,21 and thereby release the stent graft 10 in its entirety.

The invention claimed is:
 1. A stent graft for inserting into a bloodvessel of a patient, having a hollow cylindrical body with a blood sideand a vessel side, wherein the stent graft has the following: a firststent graft portion with a self-expanding stent composed of successivezig-zag rings of meandering supports in its longitudinal direction, withthe zig-zag rings also having a zig-zag form in an expanded state of thestent graft, and with a first prosthesis material secured on the ringsand connecting these on the vessel side of the hollow cylindrical body,wherein, on each of its zig-zag rings, the first stent graft portionhas, on each of its rings of meandering supports, two loops which aresewn, respectively, to the meandering supports at only one fixing point,which is shared by the two loops, such that, due to the fact that theyare guided in opposite directions around the hollow cylindrical body,the latter is compressible along its entire length, wherein the fixingpoint is located at the same position for each zig-zag ring.
 2. Thestent graft as claimed in claim 1, wherein the first stent graft portionmoreover has at least one stent side branch designed to be introducedinto a vessel branching off from the blood vessel.
 3. An insertionsystem for inserting a self-expanding stent graft into a blood vessel ofa patient, wherein the insertion system has a stent graft having ahollow cylindrical body with a blood side and a vessel side, wherein thestent graft has a first stent graft portion with a self-expanding stentcomposed of successive zig-zag rings of meandering supports in itslongitudinal direction, with the zig-zag rings also having a zig-zagform in an expanded state of the stent graft, and with a firstprosthesis material secured on the zig-zag rings and connecting these onthe vessel side of the hollow cylindrical body, and wherein, on each ofits zig-zag rings, the first stent graft portion has, on each of itsrings of meandering supports, two loops which are sewn, respectively, tothe meandering supports, at only one fixing point, which is shared bythe two loops, such, that, due to the fact that they are guided inopposite directions around the hollow cylindrical body, the latter iscompressible along its entire length, wherein the fixing point islocated at the same position for each zigzag ring, and in order tocompress and insert the stent graft into the blood vessel, the insertionsystem moreover has at least one pin element designed to be threadedthrough and temporarily, fix the loops compressing the stent graft,wherein the pin element has a proximal end and a distal end, and amiddle portion lying between these ends.
 4. The insertion system asclaimed in claim 3, wherein the compressed stent graft can be releasedby pulling the at least one pin element back in the proximal directionand thereby freeing the loops that have kept the stent graft compressed.5. The insertion system as claimed in claim 3, wherein several pinelements of different length are provided for releasing different stentgraft portions.
 6. The insertion system as claimed in one of claim 3,wherein a sleeve tube is additionally provided which is arranged overthe at least one pin elements compressing the stent graft in cooperationwith the loops.
 7. The insertion system as claimed in claim 3, whereinit moreover has a handle and, within the handle, a roller via which theat least one pin element can be guided with its proximal end.